Magnetically insulated capacitor, process for electrostatic energy storage and its applications

ABSTRACT

The invention relates to a novel electric capacitor for the attainment of very high voltages and for the storage of electric energy, comprising of two concentric coaxial toroidal conductors with the inner conductor levitated, an external magnetic field coil, a thermionic cathode emitting electrons, a levitated guide electrode and a discharge tube. The stored energy can thereby be delivered in form of atomic particle beams or electromagnetic waves especially electron beams in very short times and thus with very high power. Applications are: (1) the initiation of nuclear reactions, especially thermonuclear reactions, (2) the collective acceleration of electrically charged atomic particles to very high energies, (3) Gamma-ray flash tubes, (4) the pumping of lasers, (5) micro wave pulse generators and (6) the use of the thusly generated radiation for medical purposes.

[111 3,873,930 [451 Mar. 25, 1975 Uite States atent 1 Winterberg l l MAGNETICALLY INSULATED Winterberg, The Possibility of Producing a Dense CAPACITOR, PROCESS FOR Thermonuclear Plasma by an Intense Field Emission ELECTROSTATlC ENERGY STORAGE AND Discharge, Oct. 5, 1968, Physical Review, Vol. 174. ITS APPLICATIONS 1, PP-

{76} Inventor: Friedwardt M. Winterberg, P.O.

Primary Examiner-Alfred L. Brody Box 14524, Keno Lake, Las Vegas, Nev. 89114 Michael S. Striker Attorney, Agent, or Firm [57] ABSTRACT The invention relates to a novel electric capacitor for the attainment of very high voltages and for the storage of electric energy, comprising of two concentric 22 Filed: Mar. 1, 1973 [21] Appl. No.:336,899

be delivered in form of atomic particle beams or electromagnetic waves especially electron beams in very short times and thus with very high power. Applica- {5m References Cited UNITED STATES PATENTS tions are: l) the initiation of nuclear reactions, especially thermonuclear reactions, (2) the collective acceleration of electrically charged atomic particles to XX .11 1 7/ 5 ti 3 m Int Que S 0 .m 8 m 6 B 2 I07 99 H 00.

OTHER PUBLICATIONS very high energies, (3) Gamma-ray flash tubes, (4) the b P d f D Therm nuclF pumping of lasers, (5) micro wave pulse generators m Q O and (6) the use of the thusly generated radiation tor Plasmas by Intense Relativistic E ectron Beam. medical purposes [97], Academic Press, NY. The Physics of High E1 ergy Density, pp. 370-401.

12 Claims, 1 Drawing Figure MAGNETICALLY INSULATED CAPACITOR, PROCESS FOR ELECTROSTATIC ENERGY STORAGE AND ITS APPLICATIONS BACKGROUND OF THE INVENTION A growing number of technical applications demand pulsed energy sources with both a very high energy output and power level and for certain applications with the additional property that the delivered energy can be concentrated into a small volume. The most important application for such pulsed power sources probably lies in the area of controlled thermonuclear fusion.

According to the present technical knowledge there are two principal methods by which a large amount of energy and under high power can be concentrated into a small volume. The first method uses the focussed light beam ofa pulsed laser. The second method uses for the same purpose a pulsed intense beam of relativistic electrons produced, for example, by a Marx high voltage generator [compare, for example, F. Wintnerberg Physical Review 174 212, (1968)].

The first method, using a pulsed laser permits very high power levels, but because of the high laser cost is limited in the total energy output. In contrast the second method, using a pulsed intense relativistic electron beam permits much larger energy outputs because of the much lower costs of Joule per dollar for electrostatically stored energy. The largest presently available energy storage devices to produce relativistic electron beams are in fact about -10 time larger then the largest laser systems. But even for electron beam pulse generators the cost becomes very substantial for energy outputs above several megajoule as they are probably required for thermonuclear energy release. The high cost results from the relatively low energy storage capacity of conventional capacitors and which is of the order -l Joule/cm.

These limitations therefore set the goal to find a system which can store and deliver a substantially larger amount of energy in form of an intense pulse for the same cost. In view of the important potential applications, such as the controlled release of thermonuclear energy, this goal appears to be very important.

For the solution of this problem, and on which the invention is based, the effect, known as magnetic insulation, is used which is that by application of very strong magnetic fields in ultrahigh vacuum very high voltages can be sustained [F. Winterberg, Physical Review 174 212 (1968), The Review of Scientific Instruments 41 l756 (I970), 43 814 (1972), R. Miller, N. Rostocker and l. Nebenzahl, Bulletin of the American Physical Society 17 1007 (1972)]. It was shown that ifa strong magnetic field is applied parallel to the surface of a body at high negative electric potential electric breakdown can be prevented or substantially quenched if H E, where H and E are the magnetic and electric field strength both measured in electrostatic c.g.s. units. If, for example, H Gauss, electric breakdown can be prevented for electric fields up toSl 0 esu 3 X l0 7 Volt/cm. With these large electric fields are associated very large electric energy densities unattainable in ordinary capacitors. It should be therefore possible to store a given amount of electrostatic energy inside a much smaller volume. However, to satisfy within a vacuum everywhere the condition H E requires that the negatively charged conductor is not in physical contact with some external structure. This, for example, can be achieved by magnetic levitation of the negatively charged conductor. In an older published version for such an electrostatic energy storage device utilizing the magnetic insulation principle [F Winterberg, Physical Review 174 212 (1968) and The Physics of High Energy Density, Academic Press, New York (1971) p. 370] it was proposed to magnetically levitate a toroidal conductor, whereby the strong magnetic field was generated by superconducting windings within the torus itself. The electric charging of the torus would then have to be performed by an high energy electron accelerator. Although such a device promised the storage of large amounts of energy, it had a number of disadvantages. First, the device depended on an expensive superconducting system of substantial dimensions, second, it depended for the charging on an expensive electron accelerator, and third, because of the limitations of the electron current drawn from the accelerator it may have required rather long charging times, thus limiting the average power level for a repetitive pulsed operation.

SUMMARY OF THE INVENTION In the invention presented here, the requirements to use expensive superconductors or electron beam accelerators is completely eliminated. The charging is done. inductively at high current levels associated with short charging times and thus high average power levels for a repetitive discharge of operation. This can be done by two concentric toroidal conductors within a toroidal magnetic field coil. The iner toroidal conductor is not permitted to have any physical contact with respect to the outer toroidal conductor which for example, can be accomplished by magnetic levitation of the inner toroidal conductor. The space in between the inner and outer toroidal conductor is a hard vacuum. Near the surface of the outer toroidal conductor is a cathode, emitting electrons, for example by thermionic emission. If the magnetic field created by the toroidal magnetic field coil rises in time the electrons emitted by the cathode will be transported by the inwardly moving lines of force onto the inner conductor which is thereby charged up negatively. The magnetic field rising in time can be chosen always larger than the electric field rising in time as a result of the charging process. In this case then as long as E, the magnetic field will prevent electric breakdown which is the effect of magnetic insulation. The outer conductor at the same time will be charged up positively such that the inner and outer conductor form an electric capacitor.

After the electric field in between the inner and outer conductor has reached a critical value, such that E approaches H, at a properly placed breakdown gap in between the inner conductor and a guide electrode penetrating the outer conductor through a circular hole, the inner conductor will discharge itself onto the guide electrode. At the end of the guide electrode located inside a conducting discharge tube is an anode window followed by a drift tube. From the end of the guide electrode electrons are emitted which after passing through the anode window will form an intense electron beam.

Instead of an anode window the electron beam can be also projected into a drift tube with an axial externally applied magnetic field focussing and guiding the beam.

By connecting the toroidal magnetic field coil to a periodically varying external power source, a sequence of beam pulses can be generated with high frequency and thus high power level.

BRIEF DESCRIPTION OF THE DRAWING The sole FIGURE of the drawing is a perspective cross-sectional view of an example of the embodiment of the invention in a magnetically insulated capacitor.

DETAILED DESCRIPTION OF THE INVENTION One design example of the proposed invention in the single FIGURE showing a cross section through a toroidal machine. The machine has two concentric electric conductors of toroidal symmetry. In the single FIGURE 1 is the inner and 2 the outer conductor. The inner conductor l is not permitted to have any physical contact with outer conductor 2. This can be, for example, achieved by magnetic levitation of the inner conductor with the aid of auxiliary feed-back controlled external magnetic field coils, not shown in the FIGURE, and by making the inner conductor or part of it of a ferromagnetic substance, The space in between the inner and outer conductor must be a hard vacuum.

A time dependent magnetic field is applied in between the inner and outer conductor and which must be parallel or nearly parallel to the conducting surface of the iner conductor. The magnetic field can thereby be most easily produced by a toroidal magnetic field coil 3 which surrounds the outer conductor. This coil 3 is connected to an external power source at the coil terminals 4 and 5.

Although the single FIGURE shows a circular torus with circular cross sections of the inner and outer conductor as well as a circular cross section of the magnetic field coil, it is also possible to use non-circular tori and non-circular cross sections having the same topological properties.

The inner and outer conductor have a nonconducting gap 6 and 7, which permits the time dependent magnetic field generated by the coil 3 to flow freely into the space in between the outer and inner conductor and also into the space within the inner conductor. It is however, also possible to do without these gaps if the electric conductivity of the outer and inner conductors are sufficiently low as it is for example, the case for semiconductors. Instead of one gap it is also possible to make a number of gaps which in addition and by choice can be filled out with either a semiconducting or insulating material. In the single FIGURE the inner conductor is drawn hollow, but it is also possi ble that this conductor is either compact or filled with a nonconducting or semiconducting substance.

Within the outer gap, or within the outer conductor is a thermionic electron emitter cathode 8, which by aaid of an auxiliary voltage source 9, emits electrons into the space in between the outer and inner conductor. Instead of one such emitter cathode can be a number of such cathodes, or any number of any other electron emitting cathodes, for example, field-emitting cathodes.

If the externally applied magnetic field is increased in time by an electric current input into the field coil 3, the electrons emitted from the cathode 8 are deflected onto orbits I0, and are transported by the inwardly moving magnetic field lines until they reach the inner conductor and detach themselves from the magnetic field lines thereby charging up negatively the inner conductor. The outer conductor 2 at the same time is charged up positively. Therefore, both inner and outer conductor form an electric capacitor. The electric field E created by the electric charging process grows in proportion to the externally applied variable magnetic field H such that h E for all times during the charging process. By the aid of the external and variable magnetic field the capacitor not only is charged up inductively but at the same time is also prevented by it from having a vacuum breakdown.

Because of the large attainable magnetic fields it can be expected that the described type of magnetically in' sulated capacitor can be charged up to very high potentials. Let us for example, assume that the magnetic field reaches a value ofH alO Gauss which means that E 3 X 10 Volt/cm. Therefore, for a gap in between the inner and outer conductor which is assumed to be 30 cm the voltage of the capacitor would be VSIO Volt. Furthermore, the energy stored in such a device would be considerable. If, for example, the volume occupied by the electric field is 10 cm, which is a rather modest volume if compared with conventional capacitors, than an energy ofe$40 MJ could be stored. The discharge time T of such a capacitor is of the order (volume)" velocity of light -3 X 10' sec. The discharge current is given by I-e/V-r- 1O Ampere. These values are far beyond of what any conventional machine operating with ordinary capacitors can achieve. Moreover such a machine can quite conceivable be built substantially larger, for example larger by a factor in volume. This would lead to a stored electrostatic energy of several gigajoule. But even in this case the magnetization of the field coil and thus inductive charging could still be performed with a unipolar d.c. machine.

After the voltage has reached its peak value, whereby E begins to exceed H, controlled breakdown will occur at the breakdown gap 11 in between a protrusion of the inner conductor and an auxiliary guide electrode 15 which has the form ofa rod. As shown in the single figure this guide electrode is placed in the center of a coaxial conducting discharge tube 12. For this configuration the guide electrode has to be levitated, which here again can be most easily achieved by making the guide electrode of some ferromagnetic material to be suspended by feedback-controlled external magnetic field coils. The coaxial conducting discharge tube, is connected to and on the same potential as the outside toroidal conductor. During the charging up of the inner toroidal conductor, the guide electrode must be kept at the same potential as the outer conductor and the discharge tube. This will most probably happen automatically by a small field emission current from the guide electrode onto the conducting discharge tube.

After breakdown has occurred in between the breakdown gap lll, an intense beam of electrons will propogate along the surface of the guide electrode in a way similar as has been observed by Bennett et al., for a dielectric rod[W. H. Bennett et al. Apl. Phys. Lett. 19 441 (1971)]. In propagating along the surface of the guide electrode, the electron beam will magnetically insulate itself against radial breakdown towards the coaxial tube. If, for example, the guide electrode has a diameter of 2 cm and the electron current is 10 Ampere, then a selfmagnetic field of H-2 X 10 Gauss will be established by the beam, which is more than sufficient to ensure complete magnetic insulation of the beam against radial breakdown. For this to show assume, for example, that the discharge tube has a radius of r-l cm and that the voltage is V-l0 Volt. In this case an electric field of E- V/rl0 Volt/cm- 3 X 10 esu is set up, so that clearly E H.

After having reached the end of the guide electrode the front of the electron beam faces the anode window 13. At the high eontemplated energies the electron beam will pass through the anode window into the drift tube 14 without any appreciable energy loss. Of course, this arrangement can be used for emitting ions in which case the inner torus acts as a cathode and the anode window is replaced by a cathode window.

For the given example the power of electron beam is of the order IV Watt. Furthermore, since the inductive charging process can be done very fast, for example in a fraction of a second, the machine can work in a rapid sequence at very high average power levels unattainable for any conventional particle accelerator.

The charging current I is computed from the condition 1,1- 11' where 1- is the charging time. Put for example, 1-, [0 sec, it then follows for the above given values of I and 7 that I, 3 Ampere, which can be easily generated by thermionic emission. The power for the charging process is of the order 1 V 3 X 10 Watt and could be drawn from a conventional ac. power source. For large power levels a unipolar generator can be used.

The two most important applications of the described machine are for controlled thermonuclear fusion and for the collective acceleration of ions to ultrahigh energies.

1. It is believed that thermonuclear fusion can be achieved by the concept of thermonuclear microexplosions if the following conditions can be met: (a) An energy source must be available to deliver an energy of several megajoule within 10 see. (b) The energy source must be capable of concentrating the energy into a volume which is a small fraction of a em A machine of modest dimension can easily meet the first condition. Since the energy is delivered in form of an intense relativistic electron beam the energy can be concentrated into a very small volume if the strong selfmagnetic forces acting on the beam are utilized. In this way the second condition can be met. The energy and power which can be delivered by such a machine may even make possible the release of thermonuclear energy from the deuteriumdenterium reaction.

2. The prospect of collective ion acceleration [V. l. Veksler. in Proceedings Cern Symp. High Energy Accelerators, Geneva 1956 p. 80] becomes especially very interesting at the contemplated electron beam energies and intensities. If an ion is placed into an intense stream of electrons then by interaction with the beam it may acquire the same velocity as the beam electrons. A hydrogen ion with a mass '-"l,800 larger than the electron could in this way be accelerated up to 10 eV 1,000 BeV.

Further possible applications of the described apparatus include: (a) The use of the generated atomic particle beams for the production of transuranic elements by nuclear reactions. (b) The generation of intense X-ray flashes by the interaction of the electron beam with a solid target. (c) The use of the generated atomic particle beams to pump lasers. (d) The use of the intense electron beams to produce intense bursts of microwaves. (e) The use of the intense atomic particle beams to make beams of other rare subnuclear particles such as mesons, hyperons, etc., by elementary particle interactions of the primary beam with a target. (f) The use of two or more particle beams produced by several machines for clashing beam experiments in high energy physics. (g) The use of several machines to heat and compress plasmas for thermonuclear or other applications by simultaneous bombardment from different directions. (h) The use of the various generated radiations for medical purposes especially cancer theraphy. (i) The use of the intense beams for cutting, welding, drilling of material for industrial purposes or for rock drilling.

I claim:

1. A magnetically insulated capacitor comprising, in combination, an outer torus; a coaxial inner torusaccommodated with spacing in said outer torus and defining therewith a highly evacuated space; emitting means for introducing electrical charge carriers into said space and located in the region of said outer torus; magnetic means generating in said space a timedependent magnetic field for forcing said electrical charge carriers onto said inner torus so as to accumulate a high electrical charge thereon, and for preventing discharge of said electrical charge from said inner torus to said outer torus; and discharge means pasing through said outer torus and defining with said inner torus a spark-over gap, said discharge means being adapted for conducting said high electrical charge outside the capacitor when said electrical charge reaches a sparkover value and traverses said gap.

2. A combination as defined in claim 1, wherein said discharge means includes a discharge tube penetrating said outer torus; and a guide electrode supported in said discharge tube and defining said spark-over gap with said inner torus.

3. A combination as defined in claim 2, wherein said electrical charge carriers are electrons, and said emitting means is at least one electron emitter cathode.

4. A combination as defined in claim 3, wherein said discharge means further includes an anode window provided in said discharge tube and separating the interior of the capacitor from the exterior thereof.

5. A combination as defined in claim 2, wherein said electrical charge carriers are ions, and said emitting means is at least one ion emitting anode.

6. A combination as defined in claim 5, wherein said discharge means further includes a cathode window provided in said discharge tube and separating the interior of the capacitor from the exterior thereof.

7. A combination as defined in claim 2, wherein said guide electrode is attached to said discharge tube.

8. A combination as defined in claim 1, wherein at least one of said inner and outer tori is of electrically conductive material.

9. A combination as defined in claim 1, wherein said inner and outer tori have coinciding longitudinal axes; and wherein at least one of said inner and outer tori is provided with at least one slot extending substantially parallel to the respective one of said longitudinal axes.

110. A combination as defined in claim 9, and further comprising insulating means at least partially filling said slot.

ill. A combination as defined in claim 1, and further comprising a generator connected to said magnetic means for generating said time-dependent magnetic field therein.

12. A combination as defined in claim 11, wherein said generator is an unipolar generator. 

1. A magnetically insulated capacitor comprising, in combination, an outer torus; a coaxial inner torus accommodated with spacing in said outer torus and defining therewith a highly evacuated space; emitting means for introducing electrical charge carriers into said space and located in the region of said outer torus; magnetic means generating in said space a time-dependent magnetic field for forcing said electrical charge carriers onto said inner torus so as to accumulate a high electrical charge thereon, and for preventing discharge of said electrical charge from said inner torus to said outer torus; and discharge means pasing through said outer torus and defining with said inner torus a spark-over gap, said discharge means being adapted for conducting said high electrical charge outside the capacitor when said electrical charge reaches a spark-over value and traverses said gap.
 2. A combination as defined in claim 1, wherein said discharge means includes a discharge tube penetrating said outer torus; and a guide electrode supported in said discharge tube and defining said spark-over gap with said inner torus.
 3. A combination as defined in claim 2, wherein said electrical charge carriers are electrons, and said emitting means is at least one electron emitter cathode.
 4. A combination as defined in claim 3, wherein said discharge means further includes an anode window provided in said discharge tube and separating the interior of the capacitor from the exterior thereof.
 5. A combination as defined in claim 2, wherein said electrical charge carriers are ions, and said emitting means is at least one ion emitting anode.
 6. A combination as defined in claim 5, wherein said discharge means further includes a cathode window provided in said discharge tube and separating the interior of the capacitor from the exterior thereof.
 7. A combination as defined in claim 2, wherein said guide electrode is attached to said discharge tube.
 8. A combination as defined in claim 1, wherein at least one of said inner and outer tori is of electrically conductive material.
 9. A combination as defined in claim 1, wherein said inner and outer tori have coinciding longitudinal axes; and wherein at least one of said inner and outer tori is provided with at least one slot extending substantially parallel to the respective one of said longitudinal axes.
 10. A combination as defined in claim 9, and further comprising insulating means at least partially filling said slot.
 11. A combination as defined in claim 1, and further comprising a generator connected to said magnetic means for generating said time-dependent magnetic field therein.
 12. A combination as defined in claim 11, wherein said generator is an unipolar generator. 